(1) Field of the Invention
This invention relates generally to ultraviolet (UV) sterilization of fluids and fluid-based mixtures and, more particularly, to a microorganism neutralization UV device and method.
(2) Description of the Prior Art
Wastewater Discharge Problems and Regulatory Standards
The rapid expansion of intensive-confinement animal rearing facilities has created the secondary problem of excessive organic waste being discharged into the environment. Excessive organic waste, if not properly treated and disposed, can cause several problems, including the changing of aerobic environments to anaerobic ones with resulting suffocation and demise of aerobic species, the proliferation and spreading of human and animal pathogens, and the fouling of air with noxious microbial anaerobic metabolic byproducts. In recognition of this problem of excessive organic waste discharge, US governmental agencies have imposed restrictions on the quality and quantity of waste discharged by a point source.
Bacterial Fermentative Processes
Waste solutions containing high organic material can be treated to reduce the quantity of organic material by allowing the waste to undergo bacterial fermentation for a period of time. The fermentation can be performed under aerobic or anaerobic conditions. Generally, aerobic fermentation is the most prevalent method, as it does not require the specialized equipment and containers necessary to maintain the anaerobic state required by anaerobic fermentation. Aerobic fermentation is accomplished by simply pumping atmospheric air through the waste solution in the presence of aerobic fermentative bacteria. By contrast, anaerobic fermentation requires specialized containment vessels to prevent contact of the solution with air, and additionally requires a more elevated temperature than aerobic fermentation in order to maintain the metabolism of the anaerobic bacteria at a sufficient level to make the process efficient. However, anaerobic fermentation has recently found more application, due to the fact that this process generates methane gas, which is an energy source, as a by-product.
Fermentative processes of complex organic solutions generally rely on several species of bacteria working in synergy to effectively consume the available organic molecules for their growth. Because several species of bacteria are required to effect the degradation of the myriad of organic products found in biological waste solutions, and especially animal waste solutions, the lack of one or more of these species in the solution can severely delay or prevent the complete degradation of the organic products. Therefore, to prevent such delays, these microbes are often added to the waste solutions at or near the start of fermentation in order to act as an aid to fermnentation. These bacterial cultures were designed to ensure that no essential component of the fermentative microbial flora was deficient, and therefore that adequate fermentation would be accomplished within a normal time period. Unfortunately, several problems existed with such a treatment method and bacterial fermentation in general. First, such systems do not always give consistent performance despite the addition of microbial fermentative culture because the indigenous microbial flora may effectively out-compete the desirable fermentative bacteria, resulting in a slow and/or incomplete degradation of the waste solution and overgrowth of potential pathogens. Second, a breakdown in the supply of air or oxygen would slow the metabolism of the aerobic fermentative bacteria, with the resulting problem of slow and/or incomplete degradation of the organic waste. Finally, uncontrolled fermentation may allow the indiscriminate overgrowth of human, animal, and plant pathogens, creating an animal and/or human health hazard if discharged into the environment. In the latter case, antimicrobial feed additives retained in the waste could inhibit growth of beneficial fermentative bacteria, with the resultant overgrowth of any antibiotic-resistant endogenous flora. This situation could be potentially dangerous, should these endogenous flora be human or animal pathogens.
Thus, there remains a need for a method that is more reliable and effective in reducing the organic matter of waste solutions. Another pressing need is to reduce the number of potentially pathogenic microbes discharged in bacterially-treated waste.
Biofilter
Another method to effect the fermentative degradation of organic waste is through the use of a biofilter. A biofilter is essentially a fixed support that provides surface area for the fermentative bacteria to adhere to. The waste fluid is then directed over the support containing the microbes, at which time the microbes uptake nutrients from the passing fluid. By retaining the bacteria on a fixed surface, they are exposed to a sufficient amount of organic waste to support their metabolism. This system is generally used with dilute waste streams that would be too difficult to treat with a standard aerobic or anaerobic digester system, since nutrient availability to the bacteria in these systems is limited by the diffusion rate of the nutrients through the water. While this system can reduce the organic content of dilute waste, it cannot reduce the levels of pathogenic bacteria already contained in the waste.
Thus, there remains a need for a method that is more reliable and effective in reducing the number of potentially pathogenic microbes discharged into wetland-based treatment systems.
Modified Constructed Wetland
A more recently developed organic waste-handling method is one in which the waste stream is allowed to run into an appropriately constructed wetland. In the wetland, microscopic organisms, including aerobic and anaerobic bacteria, degrade the organic waste. In addition, protozoa, plants, and large animals, including birds, are allowed to thrive in the wetland as a means of absorbing the nitrogen and other inorganic nutrient inputs to the wetland. Unfortunately, because such a treatment system allows the contact of raw animal waste with vectors such as migratory birds, the potential exists for the spread of human and animal pathogens well beyond the immediate vicinity of the waste treatment facility.
Thus, there remains a need for a method that is more reliable and effective in reducing the number of potentially pathogenic microbes discharged into wetland-based treatment systems.
In summary, there remains a need for a wastewater treatment method that is more reliable and effective in reducing the organic matter of waste solutions and can also reduce the number of potentially pathogenic microbes discharged in bacterially-treated waste.
The present invention is directed to an organic fluid treatment method, whereby an organic fluid is pretreated by UV disinfection and then additionally treated with reactive components to effect a change in the constitution of the fluid. In the preferred embodiment, the organic fluid is directed through a UV disinfection device, then treated with microorganisms to effect the degradation of the organics in the fluid. Preferably, the UV disinfection device is a vertical riser configuration.
The present invention is further directed to a method for treating animal waste, whereby the animal waste is directed through a UV disinfection device, then treated with microorganisms to effect the degradation of the animal waste. Preferably, the UV disinfection device is a vertical riser configuration.
The present invention is further directed to a method for treating non-animal waste, whereby the non-animal waste is directed through a UV disinfection device, then treated with reactive components to effect the degradation of the non-animal waste.
The present invention is further directed to a method for manufacturing a product from a microorganism-containing fluid, whereby the microorganism-containing fluid is directed through a UV disinfection device, then treated with reactive components to produce the desired product.
Accordingly, one aspect of the present invention is to provide an ultraviolet disinfection (UV) system for treating organic waste-containing fluid, the system comprising at least one light source positioned within a housing and connected to a power source for producing a UV light output from the housing, the system including at least one optical component positioned between the at least one light source and the UV light output from the housing, thereby producing a focused, controllable UV light output that has at least one UV dose zone for providing effective sterilization of microorganisms within the water.
Another aspect of the present invention is to provide a method for purifying organic waste-containing fluid comprising the steps of providing the fluid to be treated in a reservoir; diluting the fluid; exposing the reservoir and fluid to a UV system including at least one light source positioned within a housing and connected to a power source for producing a UV light output from the housing, the system including at least one optical component positioned between the at least one light source and the UV light output from the housing; producing a focused, controllable UV light output that has at least one UV dose zone for providing effective neutralizing of microorganisms within the fluid; and adding reacting components, including microorganisms for breakdown of organic waste within the fluid.